Revert "futex: Restore one of the fast paths eliminated by 38d47c1b7075bd7ec3881141bb...

This reverts commit cb93471ed5d924b6efdfe5d0215668a9b4b91c21.

Change-Id: I7f0b45c29b3b91ba5282c51eb6b315d70ac6c813
Signed-off-by: Dima Zavin <dima@android.com>

diff --git a/kernel/futex.c b/kernel/futex.c
index 257db2460ab81542d61ba67443de70e0771c2c50..6a3a5fa1526d87d16b362e20d7d62e6809285c18 100644 (file)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -220,7 +220,6 @@ get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key)
        struct mm_struct *mm = current->mm;
        struct page *page;
        int err;
-       struct vm_area_struct *vma;
 
        /*
         * The futex address must be "naturally" aligned.
@@ -246,37 +245,6 @@ get_futex_key(u32 __user *uaddr, int fshared, union futex_key *key)
                return 0;
        }
 
-       /*
-        * The futex is hashed differently depending on whether
-        * it's in a shared or private mapping.  So check vma first.
-        */
-       vma = find_extend_vma(mm, address);
-       if (unlikely(!vma))
-               return -EFAULT;
-
-       /*
-        * Permissions.
-        */
-       if (unlikely((vma->vm_flags & (VM_IO|VM_READ)) != VM_READ))
-               return (vma->vm_flags & VM_IO) ? -EPERM : -EACCES;
-
-       /*
-        * Private mappings are handled in a simple way.
-        *
-        * NOTE: When userspace waits on a MAP_SHARED mapping, even if
-        * it's a read-only handle, it's expected that futexes attach to
-        * the object not the particular process.  Therefore we use
-        * VM_MAYSHARE here, not VM_SHARED which is restricted to shared
-        * mappings of _writable_ handles.
-        */
-       if (likely(!(vma->vm_flags & VM_MAYSHARE))) {
-               key->both.offset |= FUT_OFF_MMSHARED; /* reference taken on mm */
-               key->private.mm = mm;
-               key->private.address = address;
-               get_futex_key_refs(key);
-               return 0;
-       }
-
 again:
        err = get_user_pages_fast(address, 1, 1, &page);
        if (err < 0)